In connection with combustion engines, turbo units are often utilized which comprise a turbine which is rotated by the flow of exhaust gases. The energy which is thus absorbed by the turbine is then transferred to a compressor which is arranged to compress the air on the intake side of the combustion engine and thus increase the amount of air in the combustion chamber. This means that a larger amount of fuel can be fed to a combustion chamber in an engine, thus increasing the power of the engine.
In turbocharged diesel engines intended for, for example, commercial vehicles the starting torque from the engine is often somewhat inadequate. The reason for this is that a turbocharged engine functions as an aspirating engine at low rpm's. The fact that the engine has a starting phase which corresponds to the function of an aspirating engine means that the amount of air which is typical for a turbocharged diesel engine is not supplied. This in turn means that the amount of fuel which is injected in the engine must be limited at low rpm's, in order to minimize the amount of smoke produced until the turbo unit can supply an amount of air which will permit an increased amount of fuel.
The above-mentioned sequence of events is furthermore unfavourable since it contributes to reduced performance during the starting phase of the engine. The engine will furthermore be perceived by those travelling in the vehicle as "insufficient" during the starting phase, since it has been necessary to limit the amount of fuel supplied during the initial "aspirating engine" phase.
one way of solving the above-mentioned problem is to feed extra additional air to the engine during this starting phase in order to thus simulate the turbo function and create the possibility of feeding extra fuel to the engine. Such an arrangement is previously known from patent document CH 623382 and comprises an arrangement in an engine where compressed air is pumped into the cylinders of the engine when starting.